Process for refining copper alloys



Patented May 26, 19 36 c. '1 2 042 292 UNITED STATES PATENT oFrIcE ra'oonss FOR REFINING coPrEaALLoYs Jesse 0. Betterton and Albert J. Phillips, Metuchen, N. J., assignors to American Smelting and Refining Company, New York, N. Y., a corporation of New Jersey No Drawing. Application May 31, 1934, Serial No. 728,307

10 Claims. (01. 75-24 The present invention provides an improved to comprise soda ash, sand and coke, although process forsalvaging brass and bronze secondary other fluxing materials may be employed. The metals and miscellaneous copper alloy scrap to converter is rotated and the charge is blown withrecover the metallic values. contained therein, air in the usual manner, the air supply being I and more particularly provides a process .where controlled, however, so as to substantially com- 5 by a substantially complete separation of the. pletely eliminate the zinc without removing tin zinc, tin and lead from the copper may be acto any appreciable extent. complished. v This blowing operation results in a fume which The usual procedure for salvaging metal values contains pr y l of h zin W i w from brass and bronze secondary metals is to 'present'in the original material and about half 10 melt the charge and blow with air in a converter of the ori a a C t T fume s to remove the volatile metals, namely, zinc, tin lected in a baghouse,.Cottre1l plant, or any other and lead, and to subsequently refine the residual suitable collecting means, and is treated for the blister copper either by the usual fire-refining recovery of the metallic content thereof. A suitmethods or by electrolytic refining. This blowable method of treatment is to smelt the mixed ing operation oxidizes the zinc, tin and l ad oxide fume with carbon in the presence of a movwhichare removed from the copperas a mixed ing reducingatmosphere, which volatilizes all of dust or iume, and are collected in a 'baghous the zinc, which is recoverable as zinc oxide or blue Cottrell plant, settling chamber, or other means; p w r, While y the m operation, e lead and while various processes have been propo d oxide is reduced to metallic lead. i

' for separating the zinc from the. lead d tin After the zinc has been eliminated from the oxides (for example, by leaching with sulphuric c0livelier charge, as above explained, the accuacid), only a partial recovery of these metals is muleted r s r la is r ved r m th onobtained and the cost of the recovery is relativeverter a e efi of the pp in the ly high. a verter charge is continued by blowing the con- 2 The present invention has for one of t -gen-' verter until substantially the entire tin content eral objects the providing of an improved proc- 'Tesidllal lead nd Zinc Contents of the Charge ess for separating the zinc, tin and lead from have heeII'JOImed n a slag- This a s septhe copper contained in bra bronze a d i larated from the residual metal in the converter, l eous copper alloy scrap. which is partially refined or blister copper, it A further object of the invention is to provide being pp of course t a t e Slag contains a a process wherein the aforesaid separation is paratively large amount of copper resultin accomplished by the production of two general from the blowing- Separated S ag s reproducts, namely, a fume containing practically turned into t Converter during treatment o all of the zinc together with about half of the the u i -of y, the l b in a I lead, and the other a slag containing practically added to the convertel charge after mall of the tin with relatively smaller. amounts of pletion of the Zinc I lead and larger amounts of copper. The introduction of the slag as aforesaid, after A still further object of the present' invention the zinc blow, and further blowing o the on- 40 is to provide a process "of utilizing the aforesaid ve pr at tin-rich S in W ch he 4.

' slag to produce a further slag in which the tin t a Copper are present in approximately the content is concentrated, this last mentionedslag ratio o 1.11, re being l r a ou ts of being treated to effect a separation and recovery 'lead and zinc also present. This Skim is eof the. metal values contained therein in a simmoved and is subjecte to the improved treatment ple and effective manner. forming the substance of this invention.

Other objects of the invention will appear here- I a an with t present v nti n, it inafter, the novel features and combinations be haS been found that m e p v d results F ing set forth in the-appended claims. are obtained by reducing this tin skim to metal In accordance with the present improved procand Separating 'thefiomponehts the metal by ess, the secondary brass or bronze is melted in a. leaching. It h been found in practice that 50 reverberatory furnace or other suitable .meltin this treatment of the tin skim offers distinct adfurnace, and the resulting molten metal is transvanta s ve d t leaching t etin sk m ferred into a converter of standard constuction. as it comes from the converter. In this direct A small amount of a flux is charged on top of the leaching operation, difficulty has been experimolten metal. A desirable flux has been found enced owing to the colloidal nature of the com- 1 ponents of the tin" skim, which causes great -difiiculty in settling and other troubles in manipbe readily handled for the ultimate recovery of the values of the material. To this end, in accordance with v the present invention, the tin skim from the converter is taken to a cupola or blast furnace, where it is smelted to metal which is found to contain, approximately, onethird tin, one-third cooper, slightly less than onethird lead, and small amounts of zinc and iron. It, will be evident, of course, that the major part of the zinc is eliminated as fume during the aforesaid reduction, and the bulk of the iron content of the tin skim is eliminatedin the slag.

The metal resulting from this smelting operation is an alloy of approximately the above-indicated composition and is found to be in a condition which is readily granulatable and crushable. It is accordingly granulated from the furnace, and crushed and ground in accordance with wellknown procedure. The crushed and ground material is roasted, fiash roasting being sumcient in many instances and then leached with sulphuric acid. It is found that this leaching of the roasted product proceeds smoothly, and the aforementioned diificulties due to slow-settling and to the colloidal nature of the leached products when direct leaching is carried out, are completely obviated in the present improved operations.

During the leaching, the copper will be converted into soluble copper sulphate, the lead will be converted in part into lead sulphate and the tin will remain as tin oxide. The lead sulphate and tin oxide, being insoluble, will be present together in the residue, together with traces of zinc, copper, and iron. The major portions of the small quantities of zinc, and iron remaining after the smelting will be converted: into soluble zinc and iron sulphates.

The copper is recoverable from the sulphate solution by any one of the usual methods, such as by cementation on iron, electrolysis, precipitation as basic sulphate, etc. The unleached residue is convertible by smelting with a suitable flux, such, for instance, as soda ash and sand, to

form a solder which upon conventional refining.

is sold as such. w

Among the advantages inherent to the present process which are not afforded by existing methods of direct leaching of copper tin skim,

there maybe mentioned the fact that mass of material to be handled by the present procedure is practically cut in half. This decreased bulk of material renders the leaching operation very much easier to perform and also the smelting in the furnace removes from the material to be leached the bulk of the silicon and caustic materials, then entering the slag in the furnace,

and the presence of which in the material to be leached render the settling and filtering of the residue from the filtrate exceedingly difiicult.

Furthermore, the roasting procedure is much easier to carry out on the powdered metal than it is on powdered tin skim, since in the case of the metal, thehigh heat of oxidation of the metal aids in the progress of the roasting, whereas in the latter case'theamount of heat liberated by the conversion of cuprous to cupric oxide is negligibly small and the reaction isnot selfperpetuating, making it difiicult to obtain a dead roasted product. Also, by removing the zinc from the metal in the form of fume in the blast furnace, sulphuric acid is not consumed by this element during the leaching operation, while the removal of the iron in the slag of the blast 5 furnace results in a decreased amount of hard head" in the final solder obtained.

While certain novel features of the invention have been disclosed and are pointed out in the annexed claims, it will be understood that various oinissions, substitutions and changes may be made by those skilled in the art, and that it is intended to embrace within the scope of this invention such'modifications and changes as may be necessary to adapt itto varying conditions and uses.

What is claimed is:

1. The process of refining copper alloys containing zinc and tin for the removal of the zinc and tin therefrom, which comprises melting the alloy, blowing the moltenalloy with regulated; quantities of air to effect a selective volatilization K of the zinc substantially free from tin, continu- I I I ing to blow the remaining alloy to refine the copper and to produce a slag containing substantially all the tin of the alloy together with relatively large amounts of copper, adding such slag to a subsequent charge of the alloy during refining thereof to produce a concentrated tin slag or tin skim containing smaller amounts of copper than the aforesaid slag, separating the tin skim, smelting the said tin skim to metal, roasting the said metal, leaching the resulting roast, and recovering the metal values from the resulting solution and' residue.

2. The-process of refining tin skims containing copper, tin and zinc, which comprises smelting the said shims to convert the same to metal with elimination of the major portion of the zinc therefrom, roasting the residual metal thereby rendering the copper in readily leachable form. 4 leaching the resulting roasted product and recovering the metal values from the resulting solution and residue.

3. The. process of refining tin skims containing copper, tin,'and zinc, which comprises reducing the said skims to metal while eliminating the major part ofthe zinc, roasting the resulting metal to convert the copper content into a readiiy leachable form, disolving the copper so con:- verted, separating the solution from the resulting residue, and treatingboth the solution andthe residue to recover the values therefrom.

4. The pr ess of refining tin skims containing copper, tin, lead and zinc, whichcomprises reducing the said skims to metal while eliminating the major part of the zinc, roasting the resulting metal thereby converting the copper into a readily leachable form, dissolving e the copper from the roasted product, separating the copper solution from the residue containing the tin and 50 v lead values, recovering the copper from the copper solution, and converting the tin-lead residue into solder metal.

5. The process of refining tin skims containing copper, tin, lead, and zinc, which comprises charging the said skims into a blast furnace, smelting the skims therein to metal while eliminating substantially all of the zinc therefrom, granulating and crushing the. resulting metal, roasting the same, leaching out the copper from the roasted product, leaving the lead and tin as residues, recovering the copper from the resulting copper leach, and converting the lead and tin residues to metal.

6. 'I'heprocessof'refiningtinskimscontaining'" principally copper and tin with or without smaller amounts of lead and zinc, which comprises smelting the skims to metal while eliminating substantially all of the zinc, roasting the resulting metal, and treating the roasted product for recovering the metal values thereof.

'7. The process of refining tin skims containing principally copper and tin, with or without smaller amounts of lead, zinc and iron, which comprises smelting the skims to metal in the presence of a flu): adapted to eliminate substantially all of the iron as a slag and under conditions enabling substantially complete elimination of the zinc as a fume, roasting the residual metal, leaching the roasted product to separate the copper from the tin and lead, recovering the copper from the resulting solution and re- -ducing the tin and lead residue to metal.

8. The process of refining copper tin skims containing relatively small but appreciable amounts of iron and zinc, which comprises tive volatilization of substantially all of the aim with negligibleamounts of tin, roasting the resulting metal, and recovering the values thereofv from the resulting roasted product.

9. In the refining of tinskims containing copper, tin, lead and zinc, the improvement which comprises smelting. the skims to metal while eliminating substantially all of: the zinc therefrom, oxidizing said metal and leaching out the copper from the oxidizedproduct leaving the tin and lead as. residues adapted to be converted as fume and-slag respectively, granulating and- 

